The present invention generally relates to avionics systems and more particularly relates to a method for simplifying the entry of radio frequencies into aircraft flight control systems.
Aircraft typically have a number of radios for communications and for navigation. In order to control the operation of these radios, many commercial aircraft utilize Radio Management Units (RMUs) as control heads that allow the entry of radio frequencies by selecting a field on a display associated with the RMU and turning, for example, a dual-concentric knob until the desired frequency appears on the display. Newer aircraft utilize Multifunction Control and Display Units (MCDUs) as the control head for all the aircraft""s communications and navigational needs, and as the controller for the aircraft""s flight plan information. Combining most navigation, communication, and flight planning functions into one unit also saves space and weight, which is desirable in any aircraft. In order to enter a radio frequency into an MCDU, a keypad is provided for the pilot or crewmember to manually enter the desired frequencies into the system. The MCDU may also have alternate data entry mechanisms such as rotary switches or the like for entering frequencies or other data.
Depending upon the type of radio, navigation radios, which may include VOR navigation, ADF navigation, or any other navigation system, or communications radios, and the frequency spacing provided by the radio, entering a frequency can require up to seven keystrokes. During the entry of radio frequencies the crewmember must concentrate upon the MCDU and its display to ensure accuracy of the entries. This requires the crewmember to constantly observe the display to the exclusion of observing th e surroundings of the aircraft.
Pilots and other crewmembers have sought relief from the need to type frequency entries that include the decimal point. A complete entry for a Very High Frequency (VHF) communications radio that uses 8.33 KHz frequency spacing consists of 7 charactersxe2x88x923 digits to the left and right of a decimal point. A complete VHF navigation frequency or a VHF communications frequency at 25 KHz spacing requires 6 charactersxe2x88x923 to the left and 2 to the right of a decimal point. A complete Automatic Direction Finder (ADF) frequency requires 5 or 6 charactersxe2x88x923 or 4 to the left and 1 to the right of the decimal point. By using knowledge of the acceptable frequency range, spacing, and common pilot/air traffic controller shorthand for each radio type the number of characters required for some entries can be reduced to as few as two characters.
Accordingly, it is desirable to simplify and shorten the making of keypad entries of radio frequencies into an MCDU. This also requires that a means to validate the entry and a syntax that the crewmember must use for that entry be provided. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.
The foregoing and other desirable features may be accomplished by providing a method for expediting the entry of a radio frequency into a radio control device by allowing entry of only a portion of the actual frequency desired comprising the steps of parsing the portion of the actual frequency entered, comparing the portion of the actual frequency entered to known characteristics of permissible frequencies, choosing a permissible frequency that is uniquely compatible with the portion of the actual frequency entered, and entering the uniquely compatible frequency into the radio control device.